The invention relates to an electromedical apparatus for interference current treatment comprising at least two current circuits, wherein the current circuits are activated either by a generator for the purpose of digital generation of signal frequencies and are interconnected via phase control circuits, or said current circuits are activated by separate generators for the purpose of generating signal frequencies of small deviation (of low frequency differences).
In the case of current stimulation apparatus according to the interference principle, an intensity control is to be possible simultaneously and uniformly in the individual current circuits; this means that no noticeable synchronization faults can be permitted to occur between the channels of the current stimulation apparatus.
Up to the present time, the current intensity of the current circuits was controlled by multicircuit interference apparatus comprising multiple potentiometers. Basically, simultaneously several potentiometers are activated with a rotary knob by the operator. The synchronization error of conventional multiple potentiometers, however, lies approximately on the order of magnitude of .+-.3 db. As a consequence of this, undesired shifts in the intensity progression of the individual channels can effectively already result. The same accordingly applies when the intensity progression of the current circuits is controlled by the steepness (or slope) of the input/output transfer characteristics of field effect transistors. Since the steepness of the transfer characteristic and the so-called "pinch-off-voltages" of such components can vary greatly, it is necessary, in this instance, to reckon with a considerable outlay of adjustment elements and adjustment time.